Note: Descriptions are shown in the official language in which they were submitted.
1 ~ 6~9~
Background of the Invention -
The ever-increasing demand for hydraulically
operated telescoping crane booms of greater load lift-
ing capacity and the resulting increases in size of the
telescoping booms has created a need for a less massive
mechanism for extending and retracting the telescoping
boom. In smaller conventional hydraulically operated
telescoping booms, the hydraulic cylinders used to ex-
tend and retract the m~a~e boom sections are located
within the base se~tion and within all of the outward
moving boom sections except the fly section of the boom,
in some cases. As the boom increases in si~e and in
its number of telescoping sections, the weight of this
hydraulic cylinder mechanism becomes intolerable and
in its conventional form tends to defeat the purpose
of increasing the boom size. It is the objective of
this invention to deal effectively with this problem,
and more particularly to provide a lighter weight ex-
tending and retracting cylinder arrangement in the form
of a single cylinder whose weight can be concentrated
within the base section of the crane boom.
It is a further feature and objective of the
invention to provide on the boom base section in con-
cert with the single boom extending and retracting
cylinder thereof a latching assembly including indepen-
dently operable individual spring activated and power
retracted latching or locking pins for each movable
boom section, so that each such section can be positive-
ly and safely locked in the fully extended or fully re-
tracted position relative to the next innermost sectionof the boom.
A still further object of the invention is to
provide a more reliable and more positive extending and
retracting mechanism for each individual boom section
1 3 60g~1
in proper sequence. This mechanism involves opposite
side intermeshing fingers, each pair of which in the
extended or active position under spring loading de-
fines a recess for capturing an extending and retract-
ing rigid plate on each individual boom section. Thespring-urged fingers are retracted by associated power
means to enable the free passage thereover of movable
boom sections whose extending and retracting plates do
not require capturing in the creation of a particular
desired boom configuration.
Another important aspect of the invention re-
sides in a precision guidance system on the movable
boom sections at the rearward ends thereof for a sled
structure which closely surrounds the single boom ex-
tending and retracting cylinder whose rod end isanchored in the base ~ection at the rearward end there-
of. The sled structure is equipped with wear pads in-
cluding inclined pads at its fore and aft ends which
can pas8 over cooperative stepped lands at the rear
ends of the movable boom sections during extension or
retraction thereof by operation of the single cylinder.
In general, the present invention is character-
ized by compactness of construction, efficiency and
reliability of operation, maximum safety in operation,
and overall practicality from a manufacturing stand-
point. Various additional features and advantages will
be apparent to those s~illed in the art during the
course of the following detailed description~ by refer-
ence to the accompanying drawings, in whichs
Figure 1 is a side elevation of a crane boom
- embodying the present invention.
Figure 2 is an enlarged fragmentary side
elevation, partly in cross section showing the boom of
Figure 1 in a retracted state.
1 ~ 609~
Figure 3 is a rear end elevational view of
the boom.
Figure 4 is a transverse vertical section
taken on line 4-4 of Figure 2 showing the boom base
and inner mid-sections.
Figure 5 is an enlarged transverse vertical
section taken on line 5-5 of Figure 2.
Figure 6 is a similar section taken on line
6-6 of Figure 2.
Figures 7, 8 and 9 are views similar to Figure
4 showing the rearward ends of the boom center mid-
section, outer mid-section and fly section, respec-
tively.
Figure 10 is an enlarged fragmentary side
elevational view of a boom e~tension and retraction
cylinder, associated sled and finger means.
Figure lla iæ a fragmentary plan view of
finger retraction means on one side of the sled in
the non-retract position.
Figure llb is a similar view of finger retrac-
tion means at the opposite side of the sled in a re-
tracting position.
Figure 12a is a fragmentary horizontal sec-
tion taken on line 12a-12a of Figure 10, and corres-
ponding to Figure lla.
; Figure 12b is a similar section corresponding
to Figure llb.
Figure 13 is an enlarged cross section taken
on line 13-13 of Figure 12b.
3 Figure 14 is an enlarged fragmentary side
elevation of a boom latching pin assembly and power
retracting means on the boom base æection, the other
boom sections being shown retracted.
Figure 15 is a fragmentary vertical section
taken on line 15-15 of Figure 14.
1 ~ 609~
Figure 16 is a staggered horizontal section
taken on line 16-16 of Figure 15.
Figure 17 is a fragmentary vertical section
taken on line 17-17 of Figure 15.
DescriPtion -
Referring to the drawings in detail, wherein
like numerals designate like parts, a multi-section
tèlescopic crane boom 20, such as a five section boom,
includes a base section 21, inner mid-section 22, center
mid-section 23, outer mid-section 24, and a fly section
25. The illustrated boom has a trapezoidal cross sec-
tion for the greatest possible strength. The boom 20
is mounted on a turntable support structure 26 of a
suitable crane carrier, not æhown, and has raising and
lowering power cylinder means 27 connected between the
support structure 26 and the lower side of base section
21. The boom pivot 28 is located at the top of the
support structure 26 and near the upper rear corner of
the base section 21.
In accordance with the invention, the telescopic
boom 20 iæ extended and retracted by a single large
hydraulic cylinder 29 within the interior of the base
section 21 when the boom is fully retracted, as shown
in Figure 2. The rod 30 of this cylinder 29 is secure-
ly anchored to the rear end of base section 21 by the
anchoring structure shown at 31 in Figure 1 and 2.
The cylinder 29 proper is disposed within a sled
structure 32 and supported thereby for movement there-
with longitudinally of the boom. As shown in Figures
5 through 9, the sled structure 32 comprises a series
of vertical plates 33, 34, 35, etc. in longitudinally
spaced relationship along the sled structure, each
plates having ~ bore 36 closely surrounding the large
1 ~ 6~9~1
--6--
cylinder 29. The several plates 33,34,35, etc. are
rigidly~interconnected as a unit by top and bottom
corner members 37 and 38 of the sled 32. The sled 32
thus forms a cradle support for the cylinder 29 which
travels therewith whenever a section of the boom is
extended or retracted by operation of the cylinder, as
will be further described. A forward end cap plate 39
of the cylinder 29 carries pairs of spaced fixed lugs
40 between which extend a diagonal keying bar 41 having
its opposite ends welded to a pair of the corner mem-
bers 37 and 38 on the sled 32. The opposite end of
the sled is bolted to the rod end of the cylinder 29.
This arrangement locks the cylinder 29 against rotation
and also prevents the cylinder body from moving forward-
ly longitudinally relative to the sled.
The sled 32 is equipped with bottom wear pads42 and forward and rear end inclined wear padæ 43 and
44. The bottom wear pads 42 normally slide on the
bottom walls of the respective boom sections 21, 22,
23, etc. during extension and retraction of a particu-
lar boom section. The inclined wear pads 43 and 44 en-
able the sled to slide over rear end ramps 45,46,47 and
48 of the boom sections which are at slightly different
elevations. Figure 2 showing the arrangement of the
wear pads omits the normal bending of the cylinder and
rod along its length, and Figure 1 also omits this and
the normal bending and cocking of the boom sections
which increases as the length of the boom increases.
This omission is for the sake of simplicity of illus-
tration. Therefore, in actuality, the wear pads 42 arein sliding contact with the bottom walls of the several
boom sections during extension and retraction opera-
tions. The several boom sections themselves have lower
wear pads 49 and mountings ~0 for upper wear pads, not
1 ~ 6093~1
shown. The boom sections also have lower wear pads,
not shown, in the areas of the ramps 45,46,47 and 48
that engage the bottom corner members 38 at various
times to support the sled.
At the rear end of each boom section, with
the exception of the base section 21, there is provided
a rigid vertical plate 51,52,53 and 54. These several
plates form important elements in the full extension
and full retraction of the individual boom sections
22... 25 selectively by the cylinder 29. As shown in
Figures 4 and 7 through 9, the vertical plates 51...54
have top reinforcing members 55 and 56 rigid therewith,
and the vertical plates define aligned sled guidance
openings 57 which are of the same width on each tele-
scoping boom section so that the moving sled and
cylinder will be properly guided. The generally rec-
tangular openings 57 also have top guidance edges and
top tapered extensions 58 to accommodate a relatively
stationary longitudinal channel member 59 serving to
mount a series of limit switches 60 corresponding in
number to the movable boom sections 22,..25. During
movement of the cylinder 29 and sled 32, the actuators
61 of these switches are successively engaged by a
raised cam 62 on the top of sled 32 near its rear end.
The switches 60 operate indicator means, n~ shown,
such as lights, to signal the approach of engagement
of fingers, yet to be described, on the sled 32 with
the respective extending and retracting plates 51...54
of the movable boom sections, and indicate the location
of the sled at all times.
The forward end of channel member 59 is equipped
with a wheel 63 rollingly engaging a top plate on the
sled 32. The rear end of channel member59 is pivotally
suspended at 64 from a torque box 65 surrounding the
~`~6~
boom pivot 28 and is biased downwardly on the sled 32
by a spring means 66.
On opposite sides of the sled 32 near its
rear end are pairs of fingers 67 which coact with
the vertical plates 51...54 in the selective full ex-
tension or full retraction of the individual movabl~
boom sections by the single cylinder 29. As ~est
shown in Figures 12a and 12b, the pairs of fingers are
contained within side recesses 68 of the sled 32 formed
by vertically spaced plates 69. The pairs of fingers
are biased outwardly toward driving engagement with the
plates 51...54 by spring units 70 as shown in Figures
12a, 12b and 13. Each coacting pair of fingers 67
have intermeshing teeth 71 to assure their operation
in unison. The finger8 have exterior inclinéd faces
72 and lateral shoulders 73 across the axis of cylinder
29, which shoulders define between them a recess 74
for capturing selectively plates 51...54 of the several
movable boom sections.
The pairs of fingers 67 at required times are
retracted into the recesses 68 and away from the plates
~1 through 54 by coordinated pairs of pneumatic cylinders
75 on opposite sides of the sled 32. The rods 76 of
these paired pneumatic cylinders are pivotally coupled
as at 77 with operators 78 having slots 79. ~he op~ra-
tors 78 are pivotally anchored by shafts 80 on the sled
structure 32 and their slots 79 receive pins or shafts
81 which pass through clearance slots 82 in the fixed
plates 6g of the sled structure. Pins or shafts 81 are
received through a drive opening 83 in one finger 67
of each intermeshing toothed pair, Figures 12a and 12b.
The individual fingers 67 of each pair are pivotally
attached through pins 84 to the plates 69 of the sled
structure 32.
1 ~ 6~9~1
The arrangement of the paired driving fingers
67 for the extension and retraction of the movable
boom sections is a fail-safe arrangement in that the
fingers are always biased outwardly toward interlock-
ing driving engagement with the plates 51...54 by thespring units 70. They are retracted by the pneumatic
cylinders 75 and even if these cylinders were to fail,
the fingers would prevent collapsing of the extended,
or partly extended, boom. Outward movement of the
fingers 67 is positively limited by contact of a lug
85 on one finger of each pair with a surface 86 on the
sled structure.
Another major aspect of the invention is the
provision on the boom base section 21 of a locking pin
assembly 87 for the individual movable boom sections
2~...25 in their fully retracted and fully extended
positions. It is emphasized that the assembly 87 is
bodily mounted on the forward end of stationary base
section 21 of the boom and does not travel with any of
the movable boom sections. The details of the assembly
87 are shown in Figures 1 and 14 to 17.
To cooperate with the locking pins that are
operated by the locking pin assembly 87, now to be
described, it must be understood that each movable
boom section 22...25 is provided in its bottom wall
with pairs of locking pin openings 88 and 89. The
openings 88 are close to the front end of each boom
section and the openings 89 are near and forwardly of
the rear end of the boom section, in the socketing
portion of the boom section. These openings 88 and
89 are shown schematically in Figure 1.
- Referring to Figures 14 through 17 primarily,
the locking pin assembly 87 comprises a vertically dis-
posed rectangular frame 90 having its upper and lower
1 ~ G~9~
--10--
members inclined relative to the boom longitudinal
axis, Figure 14, to compensate for the difference in
cross sectional size of the several movable sections
of the boom. The frame 90 is rigidly supported in a
vertical plane on the base section 21 by suitable
supporting and bracing structure 91, the details of
which are not completely shown and which may be varied,
and are not important to a full understanding of the
invention.
Supported on the frame 90 in side-by-side
parallel inclined axis array are pneumatic cylinders
92, 93, 94 and 95 corresponding in number to movable
boom sections 22...25 and operable to cause retraction
of spring-loaded fail-safe locking pin pairs 96. The
tops of cylinders 92... 95 are pin coupled at 97 to the
top frame member 98 which is hollow and serves as a
compressed air manifold, receiving air from an inlet
line 99, Figure 14. Such compressed air is delivered
from the manifold 98 to the pneumatic cylinders 9295
through paired T-fittings 100 into flexible lines 101
and 102 which deliver the compressed air to pairs of
solenoid valves 103 having air outlet lines 104 lead-
ing to inlet fittings 105 on the pneumatic cylinders,
behind the pistons of the cylinders. The solenoid
valves 103 enable the selective independent operation
of any individual pneumatic cylinder 92...95 to cause
retraction of the locking pins 96 from the locking
openings 88 or 89 of any particular movable section
of the boom which must be released for full extension
or ~ull retraction by the hydraulic cylinder 29 in
order to create the desired crane boom configuration.
The rods 106 of the several pneumatic cylinders
are coupled to plungers 107 through couplings 108. The
rods 106 and plungers 107 are biased by springs 109 to
9 ~ ~
retracted positions relative to the cylinders 92...95
but the rods 106 are extended by the cylinders against
the springs 109 when the locking pins 96 require re-
traction from the locking openings 88 and 89 of the
movable boom sections. The plungers 107 have guided
engagement through openings in the lower frame member
110 .
The lower ends of plungers 107 carry shoes 112
and retain shock-absorbing belleville springs 111 be-
tween them and the lower surface of lower frame member
110. Plunger shoes 112 bear upon the upper edges of
inGlined rotatable crank levers 113 secured to trans-
verse horizontal rocker shafts 114 at stepped eleva-
tions, Figure 14, on the respective boom sections 21
24 in the retracted positions. The rocker shafts 114
are held in bearings 115, in turn secured by gusset
plates 116 to the front reinforcement collar of the
respective boom section. The rocker shaft 114 and
crank lever 113 on the front of the outer mid-section
24, center mid-section 23, and inner mid-section 22
move outwardly with these sections from beneath the
shoes 112 and locking pin assembly 87, when these sec-
tions are extended, Figure 1.
At spacedlocations thereon, each rocker shaft
114 carries keyed locking pin retractor arms 117 which
cammingly engage retractor rollers 118 of the locking
pins 96 carried by cross pins 119 in the latter. The
locking pins 96 are biased upwardly toward fail-safe
locking positions with the bottom walls of boom sec-
tions 22... 25by b~ng springs 120 which bottom on
plates 121 secured to the bottoms of the reinforcement
collars of the boom sections. As clearly shown in
Figure 16, the locking pin openings 88 and 89 of the
movable boom sections are rectangular, whereas the lock-
ing pins 96 are cylindrically formed and are mounted
for reciprocation within cylindrical bore8 122, in the
front of each boom section 21...24.
1 ~ 6~93~1
- 12 -
The tops of locking pins 96 carry aluminum-
bronze bearing pins 123 to minimize wear due to sliding
engagement of the movable boom sections on the spring-
biased locking pins. The top portions of the locking
5 pins have forward notches 124 forming top forward lips
125 which can overlap the forward edge of the rectangu-
lar opening 88 or 89 for safety, as shown in Figure 16.
The rear side of each locking pin 96 has a flat face
126. This structure enables the tops of the pins to
protrude through the rectangular openings.
Each pair of boom section locking pins 96
associated with one of the rocker shafts 114 is retract-
ed in unison by the arms 117 of such shaft to release
a particular boom section from its fully retracted or
fully extended position, as required in a particular
situation. Each pair of locking pins 96 associated
with each rocker shaft is spring-biased toward locking
engagement in the openings 88 or 89 of the movable boom
sections, as previously stated. Each pair of locking
20 pins 96 associated with one shaft 114 is retracted
against the biasing springs 120 and also against the
springs 109 by the power extension of one ~f the cylinder
rods 106 for the particular pneumatic cylinder 92. . .95
which corresponds to one of the movable boom sections
25 22. . .25. In this connection, the cylinder 92 retracts
the locking pins 96 on the outer mid-section 24 for the
boom fly section 25 shown in Figure 15. The cylinder 93
retracts the locking pins 96 on the center mid-section
23 for the boom outer mid-section 24. The cylinder 94
30 retracts the locking pins on the inner mid-section 22
for the center mid-section 23, and the cylinder 95 re-
tracts the locking pins on the base section 21 for the
inner mid-section 22.
` 13~g~'
-13-
Operation -
The laterally spaced pairs of spring-urged
locking pins 96 due to their stepped arrangement, Fig-
ure 14, will lock every movable boom section 22...25
securely in the fully retracted or fully extended posi-
tion relative to the next innermost boom section due to
engagement in the locking openings 89 or 80 of the movable
boom sections. When any given boom section is retracted,
its locking pins ~6 enter the openings 88 of that boom
section and when the same boom section is extended, its
locking pins enter the openings 89. All of the pneu-
matic cylinders 92...95 for retracting the locking pins
96 remain with the assembly 87 on the base section 21
of the crane boom, while the locking pins 96 and the
associated rocker shaft 114 and operating crank lever
113 of the outer mid-section 24, center mid-section 23
and inner mid-section 22 remain with and travel with
these sections, while these elements of the base sec-
tion remain with the baæe section beneath the aææembly
87.
In the operation of the boom, varying configura-
tions can be created by use of'the single extending and
retracting hydraulic cylinder 29 and the associated
fingers 67 which drive selected boom sectionæ outwardly
or inwardly to the full extentæ of their travel where
they are individually æecurely locked by the pinæ g6.
If a short but very rigid boom iæ required, for
example, only the inner mid-section 22 will be extended
from the fully retracted and locked position in the
baæe sec~ion 21 to the fully extended and locked posi-
tion. In such case, the movable sections 23, 24 and
25 forwardly of the inner mid-section 22 will remain
fully telescoped within the inner mid-section and lock-
ed by engagement of the pairs of pins 96 in the openings
88 of these boom sections.
6~9~'~
-14-
If a boom of maximum length is required, all
of the movable boom sections can be fully extended
and locked by the pins 96 one at a time, starting with
the full extension of the fly section 25 and followed
by the ~xtension of the outer mid-section 24, and then
the center mid-section 23, and finally the extension of
the inner mid-section 22. The safe pin locking of the
extended boom section or sections will be automatic due
to the entry of the locking pins 96 into the openings
89 under influence of the strong biasing springs 120.
In forming any required boom configuration, the
forwardmost boom section which it is desired to extend
must be extended first by operation of the cylinder 29,
followed by extension of one or more rearward boom sec-
tions in succession by further operations of the hydrau-
lic cylinder 29. Similarly, when the crane boom i8 to
be retracted or collapsed, the rearmost movable boom
section, previously extended from the base section, is
first retracted by operation of the cylinder 29, follow-
ed by the retraction of successively outermost boomsections which have been previously extended.
Before any movable boom section can be extended
or retracted, the locking pins 96 for that particular
boom section must first be retracted by one of the
cylinders 92...95. Each such pneumatic cylinder is
under control of one of the solenoid valves 103, which
in turn is controlled by an operator switch, not shown
in the drawings.
Similarly, before any movable boom section can
: 3 be fully extended or fully retracted by operation of
the hydraulic cylinder 29, its particular driving plate
51, 52, 53 or 54 must enter the driving recess 74 formed
. by each pair of driving fingers 67 at each side of the
sled 32, such driving fingers being biased outwardly
from the sled at all times by the spring units 70, un-
less retracted by the pneumatic cylinders 75.
1 ~ 6~93~
As the sled 32 is driven forwardly or rearward-
ly by the single hydraulic cylinder 29, the pairs of
fingers 67 will move with it and will automatically
capture in the recesses 74 the vertical edges of the
plate 51, 52, 53 or 54 requiring advancement or retrac~
t~on. Pressure of such driving plate upon the shoulders
73 of fingers 67, Figure 12a, will only cause the fin-
gers to engage the plate more securely, because these
shoulders are eccentrically located from the axes of
pivot elements 84. This is another safety feature of
the invention.
Driving engagement of the spring-urged fingers
67 with the plates 51...54 takes place automatically
as the interior side edges of the plates cammingly en-
gage the inclined finger surfaces 72 during extensionor retraction of a particular boom section. Retraction
of the driving fingers 67 from the respective plates
~1...54 requires operation of the pneumatic paired
cylinders 75 to the poæition shown in Figure llb to
produce finger retraction as shown in Figure 12b.
Finally, to extend any retracted boom section,
the biased locking pins 96 for that particular sec-
tion must first be power retracted from the leading
locking openings 88 by operation of the correct pneu-
matic cylinder 92...95 for that particular boom section,as previously explained. After such locking pin re-
traction, the correct pneumatic cylinder 92...95 re-
mains energized, the cylinder 29 already engaged with
the selected section is extended to cause complete ex-
tension of the selected movable boom section 22...25.As the chosen boom section approaches full extension,
the corresponding pneumatic cylinder 92...95 is de-
energized and the crank lever 113 moves upwardly and
the bearing pins or pads 123 on the locking pins 96
~36
-16-
move into sliding contact with the bottom plate for
that boom section somewhat in advance of the opening
89 and as the cylinder 29 continues to advance the boom
section the pins 96 will automatically enter the lock-
ing openings 89 for that boom section, as previouslydescribed. The driving fingers 67 are then retracted,
Figures llb and 12b, and cylinder 29 is retracted to a
position where the fingers 67 can engage the next boom
section to be extended.
Conversely, to fully retract any chosen boom
section by operation of the cylinder 29, after the
driving fingers 67 are in engagement with the chosen
boom section, the locking pins 96 for that boom section
are retracted from the openings 89 by operation of one
of the cylinders 92. . .95 pushing down on the associated
crank lever 113. Following full retraction of the
locking pins 96, the selected cylinder 92...95 remains
energized. Cylinder 29 is then retracted. As the
chosen boom section approaches full retraction, the
20 selected cylinder 92. . .95 is de-energized allowing the
crank lever 113 to move upwardly and the bearing pads
123 on the locking pins 96 to move upwardly into 81 id-
ing contact with the bottom plate of the boom section
being retracted while it is still moving at a point
25 somewhat rearwardly of the openings 88. The pins 96
will slide along the bottom of the boom section and
will automatically enter the openings 88 to lock the
boom section in the retracted position.
In the full extension or full retraction of any
given movable boom section prior to locXing pin retrac-
tion, the biased driving fingers 67 will automatically
engage the proper plate 51. . .54 of the chosen boom
section to safely drive it outwardly or inwardly
following locking pin retraction,, as previously de-
1 3 6~9~
-17-
scribed, it being understood that the cylinders 75 are
operated at proper times to retract the fingers 67 so
that they may pass with the sled 32 to the proper loca-
tion for automatic engagement with the chosen plate
51. . .54.
As the retracted driving fin~ers 67 on the sled
32 approach the chosen plate 51...54, as indicated by
the limit switches 60, the cylinders 75 are de-energized,
Figure lla, and the fingers 67 are extended just rear-
wardly of the chosen plate 51...54. Further extensionof the cylinder 29 and sled 32 causes the edges of the
opening 57 of the chosen plate to engage the inclined
finger surfaces 72, as previously explained, and cam
the fingers 67 inwardly against the spring units 70
15 until the edges of the chosen plate reach the driving
recesses 74 at which time the driving fingers 67 spring
outwardly again to the extended position under the
action of spring units 70 on opposite sides of the
chosen plate.
It can be seen that the invention enables the
construction and use of much larger telescopic crane
booms having a higher load lifting capacity, and being
; comparatively much lighter in total weight than any
comparable boom having conventional hydraulic cylinders
therein. The great reduction in weight is effected by
the use of the single hydraulic cylinder 29 to extend
selectively each movable boom section and to retract
the same. The arrangement of the sled 32 and driving
fingers 67 with retracting means and the cooperative
arrangement of the locking pins 96 with selective re-
tracting meanæ enables the attainment of the main
objective of the invention, namely, the provision of a
larger and comparatively lighter weight boom with
greater lifting capacity.
~6
-18-
The terms and expressions which have been
employed herein are used as terms of description and
not of limitation, and there is no intention, in the
use of such terms and expressions, of excluding any
equivalents of the features shown and described or
portions thereof but it is recognized that various
modifications are possible within the scope of the
invention claimed.
